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CCNA Certification All-In-One For Dummies by Silviu Angelescu

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Chapter 4: Subnetting

Exam Objectives

Describing the purpose and function of subnetting

Dividing networks into smaller pieces called subnets

Understanding proper subnetwork planning

Describing classless interdomain routing

Identifying CIDR slash notation

Subnetting Class A, B, and C networks

Using hexadecimal and binary conversion

Understanding subnet zero

Identifying and using variable-length subnet masks (VLSMs)

Explaining summarization

Understanding the ANDing process

This chapter examines and provides detailed examples of how subnetting works and why it is used in so many organizations around the world. A proper understanding of subnetting is essential for passing the CCNA exam. I discuss how to create subnets and how to determine the subnet and number of hosts from the IP address. I take a look at classless interdomain routing (CIDR) and its uses and provide you with examples of subnetting from the three major classes, A, B, and C. Variable-length subnet masks (VLSMs) and summarization are also discussed.

Before even scheduling your CCNA test, you should know this chapter forward, backward, inside out, and upside down! So now I get right to it . . . Subnetting 101!

Subnetting Basics

The IP address is comprised of the network ID and host ID fields, with a logically invisible separating line dividing the two. This dividing line can be shifted, or “moved to the right,” by the network administrator to add configuration flexibility to the local-area network. Logical networks ...

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